Skip to main content

Decisive Battles of History: Pharsalus

Andrew is an avid reader of history who enjoys researching and discussing ancient Roman topics with others.

Read on to learn about the Battle of Pharsalus, a historical battle in which Caesar decidedly defeated Pompey. This ushered in the eventual fall of the Roman Republic.

Read on to learn about the Battle of Pharsalus, a historical battle in which Caesar decidedly defeated Pompey. This ushered in the eventual fall of the Roman Republic.

Political Background of the Battle of Pharsalus

After winning the Second Punic War, the Roman Republic became the dominant power in the Western Mediterranean. In the following century and a half, the legions of Rome steadily subdued the rest of the Mediterranean world, and by the time Julius Caesar began his conquest of Gaul, Rome was the Master of the known world.

The unprecedented military successes of Rome led to the widespread exploitation of the Mediterranean world by the elite of Rome, some of whom have become rich beyond all imagination. As Rome subdued all her external enemies, the elite of the Eternal City turned on each other. Thanks to the immense wealth hoarded by these elites and the military reforms of Marius, the armies of the Republic were soon turned into the private militaries of wealthy aristocrats.

Civil strife became endemic and political violence became commonplace after the murder of the Gracchi brothers in the late 2nd century BC. Soon street violence was traded for outright Civil War when Sulla marched with his legions against his political rival Marius.

Years of Civil War ended with the victory of Sulla, who for a time was the unrivalled military dictator of Rome. Despite his cruel methods, Sulla had no intentions to overthrow the Republic, and after a time of absolute power, he willingly gave up power and retired.

The decades after the retirement of Sulla were dominated by ambitious men like Crassus, Pompey and Caesar, to mention only a few of them. Two factions dominated the politics of Rome in this period: the Optimates, who were backed by most of the traditional elite of Rome, and the Populares, who were claimed to represent the interest of the poorer classes and received a much smaller backing from the patrician elite of Rome.

The Republic carved by Caesar, Pompey and Crassus

The Republic carved by Caesar, Pompey and Crassus

Caesar's Civil War

For a time, Pompey was the champion of the Populares faction, but after his impressive campaigns in Gaul, Caesar usurped this position from Pompey.

For a time, Caesar, Pompey and Crassus allied themselves and dominated the politics of the Republic. This alliance came undone when Crassus, jealous of Caesar’s victories, tried his luck as a military man.

Although he was not inexperienced as a commander, as Crassus had served under Sulla during the Civil War and crushed the revolt of Spartacus, his Parthian campaign was an utter disaster. His army was destroyed at the Battle of Carrhae, and even Crassus himself was killed.

After the death of Crassus, the two remaining allies drifted apart. Pompey sided with the Optimates, completely abandoning Caesar and the Populares faction.

Despite his great popularity among the people and his soldiers, Caesar's political situation was difficult. His term as governor of the Gallic provinces was coming to an end, and once that was done, he lost his legal immunity. From that point on, his enemies were free to prosecute him for his offences, real or imagined.

The Senate took a hard stance against Caesar and demanded that he return to Rome and disband his legions. Caesar knew that his only and best protection was his veteran legions, so he decided to ignore the demands of the Senate and marched on Rome.

Pompey had many more resources than Caesar, thanks to his vast clientele and the backing of the Senate, but these troops were widely scattered in Spain and the Roman East, while Caesar’s army was compact.

Caesar’s quick march on Rome surprised his enemies and forced them to abandon Rome and later even Italy. Pompey and his supporter fled to Greece and gathered their legions there. Caesar initially left them alone and instead marched to Spain to defeat the Pompey loyalist in his rear. He succeeded in his mission and turned to Greece.

Scroll to Continue

Read More From Owlcation

Caesar Against Pompey: The Battle of Dyrrachium

Despite his success in driving his enemies out of Italy and defeating the Pompey loyalists in Spain, the position of Caesar was not easy by any means. His overall number of troops was lower than that of Pompey, and crucially for him, his navy was net inferior also.

Caesar managed to escape Pompeyan naval patrols to transfer seven legions to Greece, but his forces were outnumbered by the Pompeian forces and struggled badly with supply problems. The two generals manoeuvred against one another for quite a time, but Pompey was reluctant to engage Caesar's veterans in a pitched battle.

Mark Antony, in the meantime, managed to cross into Greece with reinforcements and managed to avoid destruction by the superior forces of Pompey. Antony joined Caesar to bring up the number of the Caesarian force. Caesar then decided to capture the main supply depot of Pompey at Dyrrachium. He marched to the city, but Pompey remained hot on his heels. Pompey stayed close enough to Caesar to prevent him from trying a siege.

The two armies were in close proximity again, but Pompey once again refused to engage Caesar in a pitched battle. He was happy enough to let hunger do the job for him; however long it took mattered little. Caesar realised this also, then made an unexpected move.

He decided to build a long line of fortifications to pin down Pompey and cut him off from the countryside; this way, it would be Pompey’s army who ran into supply problems. Pompey responded to Caesar’s fortifications by building his own around his encampment. For a time, the two armies stared at each other from their fortifications, and on occasion, both deployed in battle formations just outside their walls but not in range of enemy missile units.

Pompey tried deceit in breaking the deadlock by luring Caesar into an ambush, making him believe that the officials of Dyrrachium wanted to switch sides. The trick only partially worked, as Caesar survived the ambush. While Caesar was away, Pompey’s men assaulted Caesar’s fortifications, but they were repelled.

The deadlock was broken when deserters from Caesar’s camp gave away a weak spot on the Caesarian fortifications. Pompey immediately assaulted the weak spot and overwhelmed the defenders. With the fortification line broken, the Pompeian camp's supply problems were solved.

Caesar realised this and tried to overwhelm the forces of Pompey who were guarding the area, but his attack did not go according to plan. A counterattack Pompey sent threw the men of Caesar into a panicking rout. Caesar later commented that had Pompey kept up the attack, instead of ordering a halt, they could have finished the Civil War that day.

The Battle of Pharsalus

With his line of fortifications penetrated, Caesar ordered a retreat. Pompey realised this too late, and the rearguard of Caesar checked his pursuing forces.

After his failure at Dyrrachium, Caesar decided to abandon the coastline. This way, he hoped to separate Pompey from his fleet, which was the lifeline of his army. Caesar raced to join his dispersed troops in the interior and succeeded in only just getting to them ahead of Pompey. The race was close, and only a few hours separated Pompey from crushing Caesar’s subordinates.

Caesar marched into Thessaly and set up camp not far away from Pharsalus. Pompey followed his rival there and set up his camp nearby. As usual, Pompey chose an excellent defensive position on a hill.

Caesar tried to provoke Pompey into giving battle several times by lining up his men in battle formation, but Pompey refused to go ahead with the battle, as he did not want to risk a fight against Caesar’s hardened veterans.

Unfortunately for Pompey, he, unlike Caesar, was only the first among equals in the Republican camp, and his colleagues constantly pressured him into fighting Caesar. For whatever reason, Pompey, against his better judgement, decided to go ahead with the battle.

He ordered his troops to line up in a battle formation on August 9, 48 BC. Caesar accepted the challenge and ordered his troops into battle formation. Pompey’s army outnumbered Caesar’s probably by 2-1, and Pompey’s cavalry from 5-1 to 7-1. Caesar cleverly anticipated Pompey’s plan of using his cavalry to win the battle and decided to put a part of the veteran infantry behind his own cavalry.

The battle began with Caesar ordering his infantry to advance against Pompey’s infantry. Not much later, Pompey ordered his cavalry forward, and as expected, they easily drove away Caesar's cavalry away. However, Caesar’s veteran infantry checked the Pompeian cavalry and routed it. Using their momentum, the infantry attacked Pompey’s force from the flank. At this moment, Caesar threw into the battle his last reserves and achieved a breakthrough.

Seeing the disaster unfolding, Pompey fled to his camp, and once the camp was under attack fled Greece altogether. Caesar won a decisive victory against his enemies, and many among those who supported Pompey decided to surrender to Caesar. Pompey fled to Egypt, but he was assassinated there on the orders of the young Pharao's advisers, who believed Caesar would be pleased to be rid of his greatest rival.


Goldsworthy, Adrian. (2008). Caesar: The Life of a Colossus. Yale UP.

Holland, Tom. (2005). Rubicon: The Last Years of the Roman Republic. First Anchor Books.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Andrew Szekler

Related Articles